Code point
U+2359
Glyph appearance depends on your fonts.
U+2359
SoU+2359 APL FUNCTIONAL SYMBOL DELTA UNDERBAR is a Unicode 16.0.0 character in the Other Symbol category. It belongs to the Miscellaneous Technical block.
Choose the representation you need, then copy its value.
U+2359
9049
⍙
⍙
E2 8D 99
2359
00002359
%E2%8D%99
\u2359
\u2359
\u2359
\2359